Problem: Nadia has dinner at a restaurant and the cost of her meal is $\$37.00$. She would like to leave a $20\%$ tip. What is her total bill including tip?
Solution: The tip amount is equal to $20\% \times \$37.00$ We can find the tip by first calculating a $10\%$ tip and then multiplying that number by two. To calculate a $10\%$ tip, move the decimal point in $\$37.00$ one place to the left. $10\%$ $\times \$37.00$ $\$3.70$ To calculate a $20\%$ tip, multiply the $10\%$ tip amount by two. $20\%$ $\times \$37.00$ $\$3.70$ $ \times 2 = $ $\$7.40$ The cost of the meal plus the amount of the tip will equal the total bill amount. $\$37.00 + \$7.40 = $ $\$44.40$ The total cost of the bill is $\$44.40$.